Letter stacker

ABSTRACT

In a device for stacking flat letters having a separating mechanism and a stacking mechanism between which the letters are stacked, the stacking mechanism capable of moving in the stacking direction along a stacking surface, and a transport path that is formed by endless vertical belts guided by way of rollers, between which belts the letters are conveyed from a loading station to the stacking mechanism, it is provided that the stacking surface has a horizontal concave curvature with respect to the side on which the transport path is located, and that the belts are deflected in the region of the transport path by a plurality of deflecting rollers that are disposed on a curve adapted to the curvature of the stacking surface in such a way that the transport path has a curvature adapted to that of the stacking surface, in the region of the transport path, the belts being disposed between the stacking surface and the deflecting rollers.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus for stacking flat letters.

In letter-processing systems, it is often necessary to store letterstemporarily between two processing cycles. For example, for couplingasynchronously-working systems or parts, storage apparatus are used. Oneletter-storing technique involves temporarily stacking the letters.

Normally, a stacker comprises a stationary separating mechanism and astacking mechanism that can move in the stacking direction, the lettersbeing stacked therebetween. The base of the letter stack is formed by astacking surface. Two endless belts that circulate around rollers form atransport path that conveys the individually-arriving letters to the endof the stack.

Between the stacking mechanism and the letter-loading loading station,the two belts form a straight section of the transport path on which thebelts run freely, i.e., they are not guided by rollers in that section.The length of this partial section of the transport path is dependent onthe momentary position of the stacker mechanism during the stackingprocess. As the letter stack grows, this partial section is shortenedproportionally. It reaches its maximum length if there is no letterstack and the stacking mechanism is located directly at the separatingmechanism.

Given a comparable engineering outlay, the storage capacity achievablewith this design is, in fact, greater than that attainable withimbricated storage, where the letters are squeezed one on top of theother, in imbricated form, between belts. However, when working with theabove-described type of apparatus, problems arise when the straightpartial section of the transport path reaches its maximum length. Insuch a case, the situation may arise that a plurality of letters arelocated on the partial section at the same time. If this occurs in amanner such that a thin letter is situated between two thick letters onthe straight section, the thin letter is not securely held by the belts.If a plurality of letters are situated between two thick letters, it canhappen that the thin ones shift over on top of each other, causing a jamin the transport path and an interruption in the operation of thesystem. An additional problem is that the free-running belts hangincreasingly lower as the length of the partial section in the transportpath increases. Both problems may lead to a maximum stacker length ofone meter for the type of stacker apparatus described above.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a stacker apparatuswith which larger storage capacities can be attained.

An embodiment of the invention entails securely holding the lettersbetween the belts of the transport path by means of a curved transportpath, and by providing multiple deflection of the belts around therollers in the region of the transport path, ensuring free movement ofthe stacking mechanism because the belts are disposed between thestacking surface and the deflecting rollers in the region of thetransport path. An apparatus according to this embodiment of theinvention therefore has a stacking surface possessing a horizontal,concave curvature with respect to the side on which the transport pathis located. The belts in the region of the transport path are deflectedby a number of deflecting rollers that are arranged on a curve that hasa curvature essentially the same as the stacking surface curvature sothat the transport path has a curvature essentially the same as thecurvature of the stacking surface, the belts being disposed between thestacking surface and the deflecting rollers in the region of thetransport path.

In one preferred specific embodiment of the invention, the stackingsurface is essentially annular. The stacking surface may comprise anumber of segments or may be embodied as a rigid disk. In oneparticularly preferable embodiment of the invention, belt bridges areprovided at the stacking mechanism and at the loading station, by meansof which bridges the outer belt is guided above or below the transportpath. In other specific embodiments of the invention, both belts areguided together by means of the same deflecting rollers that are alsoused by the transport path, or by means of additional deflecting rollersdisposed inside the ring formed by the transport path. In a further,preferred embodiment of the invention, the apparatus comprises aplurality of similar segments, with the exception of the region of theloading station and of the separating mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a stacker apparatus,

FIG. 2 shows a detailed view of the transport path 9 of the stackerapparatus of FIG. 1,

FIG. 3 shows an apparatus according to the invention having a curvedstacking surface,

FIG. 4 shows a cutout of an annular apparatus according to theinvention,

FIG. 5 shows a belt bridge,

FIG. 6 shows a further belt bridge,

FIG. 7 shows an alternative belt guide for an apparatus according to theinvention, and

FIG. 8 shows a ring storage element with segments.

DETAILED DESCRIPTION OF THE DRAWINGS

In the apparatus for stacking flat letters which is illustrated in FIG.1, a separating mechanism 1 pulls off letters, as needed, that arestacked in a stack 3 between said separating mechanism 1 and a stackingmechanism 2. Stacking mechanism 2 is movable in the stacking direction.The base of a letter stack is formed by a stacking surface 4, preferablyconfigured as a circulating conveyor belt. Two endless belts 5, 6circulate around rollers. They form a transport path 9 between a loadingstation 100 and stacking mechanism 2. Belts 5, 6 are guided freelybetween roller 7, disposed at stacking mechanism 2, and stationaryroller 8. In addition to roller 7, stacking mechanism 2 includes furtherrollers, by way of which belts 5 and 6 are guided to ensure that theletters are stacked securely. During the stacking process, stackingmechanism 2 is moved in the direction of stack 3. In this context, thelength of transport path 9 is a function of the momentary position ofstacking mechanism 2. The length is shortened proportionally as theletter stack grows. Conversely, the path reaches its maximum length ifthere is no letter stack and stacking mechanism 2 is directly situatedat separating mechanism 1. As illustrated in FIG. 2, if a thin letter issituated between two thick letters in transport path 9, the thin letteris not held securely by the belts.

FIG. 3 illustrates the basic design of an apparatus according to theinvention, having a curved stacking surface 40 that serves as the basefor the letter stack. The letter stack is located between separatingmechanism 1 and stacking mechanism 42, the latter being movable alongstacking surface 40. The two belts 5 and 6 are guided by way of aplurality of rollers 45, and form a curved transport path 43. In theregion of transport path 43, the belts are deflected multiple timesaround rollers 45. In this context, the distance between the rollers isselected to be small enough to enable the letters to be held securely.Deflecting rollers 45 are all disposed on the same side of belt pair 5,6 in the region of the transport path, so that the length of thetransport path is infinitely adjustable when stacking mechanism 42 movesalong stacking surface 40. According to this embodiment of theinvention, the entire apparatus in FIG. 3 is curved, i.e., stackingsurface 40 and the curve on which deflecting rollers 45 are arrangedhave essentially the same curvature. Stack 41 and the track of stackingmechanism 42 follow the curvature of stacking surface 40.

FIG. 4 illustrates an advantageous specific embodiment of the apparatusin which the apparatus is essentially annular. Due to the annularconfiguration of the arrangement, the endless circulation of belts 5, 6is simplified in that outer belt 5 and inner belt 6 are returned alongthe shortest path in the regions 50 or 51 between loading station 101and stacking mechanism 42. Inner belt 6 is preferably returned by way ofa stationary deflecting roller 53, which is fixedly disposed on theconcave side of curved stacking surface 52 in the region of loadingstation 101.

In a preferred specific embodiment of the invention, outer belt 5 isguided away via two belt bridges along the transport path. FIG. 5illustrates a first belt bridge 60, which is preferably connectedrigidly to stacking mechanism 42. Belts 5 and 6 are guided by way of aplurality of deflecting rollers at the stacking mechanism, with outerbelt 5 being rotated and rotated back, respectively, in its orientationby 90° by two horizontal rollers 63, 64. Belt 5 can be guided above orbelow transport path 43. FIG. 6 illustrates a similar belt bridge 61 forcrossing above or below the transport path in the region of loadingstation 101. The belt bridges permit the return of outer belt 5 on theconcave side of stacking surface 52. Therefore, the outer belt can beguided back with inner belt 6 between points C and D by way of the samedeflecting rollers that are also used by the transport path, and bydeflecting roller 53.

FIG. 7 illustrates an advantageous embodiment of the invention in whichbelts 5, 6 are returned by way of additional deflecting rollers. Thesedeflecting rollers are essentially disposed on a ring 70 insidetransport path 43. This arrangement allows endless belts 5, 6 to beexchanged, even if the entire apparatus is set up around a column, forexample.

FIG. 8 illustrates a preferred embodiment of the apparatus that isconstructed from a plurality of similar segments 81, with the exceptionof the region of the loading station and separating mechanism 80.

We claim:
 1. An apparatus for stacking flat sheets, comprising aseparating mechanism and a stacking mechanism between which mechanismsthe sheets are stacked, the stacking mechanism being movable in astacking direction along a stacking surface, the apparatus furthercomprising a transport path formed by endless belts guided by rollers,between which belts the sheets are transported from a loading station tothe stacking mechanism, wherein the stacking surface has a curvatureconcave with respect to a side on which the transport path is located,and the belts are deflected in the region of the transport path by aplurality of deflecting rollers that are disposed on a curve having acurvature essentially the same as the curvature of the stacking surface,such that the transport path has a curvature essentially the same as thecurvature of the stacking surface, the belts being arranged between thestacking surface and the deflecting rollers in the region of thetransport path.
 2. An apparatus as defined in claim 1, wherein thestacking surface is essentially annular.
 3. An apparatus as defined inclaim 2, wherein the stacking surface comprises a plurality of segments.4. An apparatus as defined in claim 2 wherein the stacking surface isconfigured essentially as a rigid disk.
 5. An apparatus as defined inclaim 4 further comprising a belt bridge at each of the stackingmechanism and the loading station, by way of which bridges an outer beltis guided above or below the transport path.
 6. An apparatus as definedin claim 2 further comprising a belt bridge at each of the stackingmechanism and the loading station, by way of which bridges an outer beltis guided above or below the transport path.
 7. An apparatus as definedin claim 6, wherein the belts are guided back by way of the samedeflecting rollers that are also used by the transport path.
 8. Anapparatus as defined in claim 6, wherein the belts are guided back byway of separate deflecting rollers that are disposed inside a ringformed by the deflecting rollers used by the transport path.
 9. Anapparatus as defined in claim 2, wherein the belts are guided back byway of the same deflecting rollers that are also used by the transportpath.
 10. An apparatus as defined in claim 2, comprising a plurality ofessentially similar segments, except for the region of the loadingstation and the separating mechanism.
 11. An apparatus as defined inclaim 1, wherein the stacking surface comprises a plurality of segments.12. An apparatus as defined in claim 11, wherein the belts are guidedback by way of the same deflecting rollers that are also used by thetransport path.
 13. An apparatus as defined in claim 1 wherein thestacking surface is configured essentially as a rigid disk.
 14. Anapparatus as defined in claim 13 further comprising a belt bridge ateach of the stacking mechanism and the loading station, by way of whichbridges an outer belt is guided above or below the transport path. 15.An apparatus as defined in claim 13, wherein the belts are guided backby way of the same deflecting rollers that are also used by thetransport path.
 16. An apparatus as defined in claim 1 furthercomprising a belt bridge at each of the stacking mechanism and theloading station, by way of which bridges an outer belt is guided aboveor below the transport path.
 17. An apparatus as defined in claim 16,wherein the belts are guided back by way of the same deflecting rollersthat are also used by the transport path.
 18. An apparatus as defined inclaim 16, wherein the belts are guided back by way of separatedeflecting rollers that are disposed inside a ring formed by thedeflecting rollers used by the transport path.
 19. An apparatus asdefined in claim 1 wherein the belts are guided back by way of the samedeflecting rollers that are also used by the transport path.